The synthesis of proteins in pigs depends on protein and essential amino acid levels in given feed. When volume and ratio of essential amino acid are optimum, the pigs can synthesize protein effectively. Once there is more protein retention in the body the pig secretes less nitrogen in the urine. Methionine is an important to protein synthesis. It is the precursor of protein syntesis process on DNA sequences. When methionine is supplied to the pigs efficiently, the liver can synthesize protein effectively. Requirement of much more other amino acids for hormone, antibody, enzyme and lean production are observed. The requirement of lysine for lean production is higher because the lean composition of lean has high volume and ratio of lysine. The appropriate ratio of methionine in diet as compared to lysine brings about the high level of lean and larger Longissimus muscle area is required (Jones and Pond, 1963). The dietary formulation containing protein from soy bean composing of low level of methionine featured with optimum ratio of methionine and lysine in the diet is utilized from the amino acids by the pigs effectively (Kamkuan, 2003; Terapuntuwat et al., 2550).

The target of this research is to investigate the effects of lysine and methionine levels by using the different methionine and lysine dietary calculated by the requirement of the pigs on the growth performance.

Materials and methodsTesting animals

This study used 33 male cross bred pigs (Large white X Landrace X Duroc), averaging 67 kg live body weight. They were fed in metabolism cages. Urine and feces were separately collected. The animals were exposed to continuous light. They were divided into 2 groups. Group 1, 27 pigs were subjected to dietary treatments. Nine formulated diets were given to 3 pigs each by the different level of lysine, 0.780, 1.025 and 1.270 % and methionine, 0.240, 0.315 and 0.390 %. Group 2, 6 pigs were fed with protein-free diet to study metabolic and endogenous nitrogen loss. Water free available.

Testing diet

The diet containing 16.83% protein composed of corn, full fat soybean, soybean meal, rice bran, broken rice, calcium carbonate, dicalcium phosphate, salt and mixture of vitamins and minerals. DL-methionine calculated in 3 different levels 0.240, 0.315 and 0.390 % and 0.780, 1.025 and 1.270 % of L-Lysine added. The details of the diets are shown in the Table 1. Other nutrition volumes were calculated according to NRC (1998) recommendation.

Recording

The experimental animals were allowed to adapt to housing and experiment conditions for 7 days and the length of experimental period was 28 days. Parameters recorded during the experiment were the first and the last weight of the week, consumed diet (measured daily), growth rate, amount of diet consumed, effectiveness of diet utilization (body weight gain per consumed diet), protein efficiency ratio (body weight gain per consumed protein) and net protein ratio (body weight gain including body weight loss of the pigs given free-protein diet) The above parameters were calculated by the following formulae ;

Experimental design

The experimental data were subjected to 3 x 3 Factorial Experiment in Completely Randomized Design. Nine treatments of formulated diets with 3 different levels of lysine, 0.780, 1.025 and 1.270 and 3 different levels of methionine, 0.240, 0.315 and 0.390 % were tested. Mean were compared by Duncan’s New Multiple Range Test (Steel and Torrie, 1980).

Results and discussions

Average weight loss of the pigs fed with protein-free diet 0 to 28 days, was 203.57 g/d. Nine formulated diets showed similar growth performances (similar to what, among the nine formulated diets or to protein-free diet). The highest weight gain was 89.87 kilogram found in the pigs fed with diets containing 0.780 % lysine and 0.390% methionine, 1.270% lysine and 0.315% methionine, while the least weight gain was 86.67 kilogram found in the pigs fed with diets containing 0.780% lysine and 0.240% methionine as shown in Table 2. In terms of amount of consumed diet, the pigs consumed the limited diet at the same level, 2000 g/h/d in week 1st, 2200, 2500 and 2600 g/d in week 2nd, 3rd and 4th respectively. The average of the consumed diet was restriced to 2325 g/h/d. Similarly growth rates were found in all 9 diets (P>0.05). The pigs fed with diet containing 1.025% lysine and 0.390% methionine tended to yield the highest growth rate, 816.67 g/h/d, and gain/feed 351.25 g/kg, as compared to the pigs fed with other diets (Table 2). The protein efficiency ratios and net protein ratios there were similarly (P>0.05). Because the pigs consumed the same amount of limited diets thus protein daily were limiting. Therefore, the measured values calculation showed the similar trend as gain/feed. The pigs fed with 1.025% lysine and 0.390 methionine tended to show the highest protein efficiency ratio (2.09) and net protein ratio (2.61). Lysine and methionine showed no relations what kind of the relationship, on pigs performance to each other.

When the lysine level was increased from 0.780% to 1.270%, the pigs showed higher growth rate from 756.35 g/d to 762.70 g/d, R2 = 0.9795. Gain/feed, protein efficiency ratio and net protein ratio showed similar trend. Increased level of methionine from 0.240 % to 0.315 % and 0.390 % seemed to increase growth rate, 723.02, 764.29 and 792.06 g/h/d respectively, R2 = 0.9874. This trend was also found in gain/feed (310.97, 328.73 and 340.67 g/kg diet respectively 0.240 % to 0.315 % and 0.390 % of methionine), protein efficiency ratio (1.85, 1.95 and 2.02 respectively) and net protein ratio (2.37, 2.47 and 2.54 respectively). The diet of finishing pigs containing 16.83% protein made of raw materials, corn, soybean, broken rice and rice bran could increase the methionine level from 0.240 to 0.315 and 0.390 %. This led to better protein quality and in these diet, increase of lysine from 0.780 % to 1.025 % yielded higher gain per feed and weight gain per day, R2 = 0.9795, however, no significant difference was found. Pigs fed with 1.025 % lysine and 0.390 % methionine diet tended to have the best highest growth rate. Ideal protein value of diet 1.025% lysine 0.390% methionine suggested that the ratio of methionine and lysine was 38:100 and sulfur-containing amino acid per lysine was 61:100. The pigs consuming methionine at 0.390 % which was close to the level of the optimum volume was higher than that suggested by NRC (1998) 0.18 %. The level of lysine at 1.025 %, the pigs could perform better productivity than those consuming 0.780 % and 1.270 % lysine that was higher than that suggested by NRC (1998). The diet containing 1.025% lysine and 0.390% methionine had 0.63 % of sulfur-containing amino acid (the ratio of sulfur-containing amino acid per lysine = 61:100) which was higher than the level of 0.47 % reported by Roth and Kirchgessner (1987), Chung et al. (1989) 0.45 % Lenis et al. (1990), 0.45 %, Loughmiller et al. (1997) 0.285 % and Knowles et al. (1998) 0.23 %. Therefore, finishing diet comprising of raw materials, soy bean, corn, broken rice and rice bran should be contain the 0.390 % methionine and 1.025 % lysine. This could bring about the best utilization of diet of the 65-90 kg live weight pigs. The effects of lysine and methionine levels on the utilization of protein should be future studied.